PR ld/13683
* ldlang.c (lang_process): Rerun lang_do_assignments before
starting garbage collection.
* ldexp.c (fold_name): Generate a reloc for defined symbols
found without an associated output section during the mark phase.
(exp_fold_tree_1): Continue processing an expression, even if we
are unable to fold it, if we are in the first two evaluation
phases.
* ldexp.h (enum lang_phase_type): Add descriptions of the phases.
* ld-gc/pr13683.c: New test source file.
* ld-gc/pr13683.d: New test control and output file.
* ld-gc/gc.exp: Run the pr13683 test.